align isPowerlineGlyph across renderers (#3743)

src/browser/renderer/BaseRenderLayer.ts

@@ -14,7 +14,7 @@ import { AttributeData } from 'common/buffer/AttributeData';
 import { IColorSet, IColor } from 'browser/Types';
 import { CellData } from 'common/buffer/CellData';
 import { IBufferService, IOptionsService } from 'common/services/Services';
-import { throwIfFalsy } from 'browser/renderer/RendererUtils';
+import { isPowerlineGlyph, throwIfFalsy } from 'browser/renderer/RendererUtils';
 import { channels, color, rgba } from 'browser/Color';
 import { removeElementFromParent } from 'browser/Dom';
 import { tryDrawCustomChar } from 'browser/renderer/CustomGlyphs';
@@ -428,12 +428,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
   }
 
   private _getContrastColor(cell: CellData): IColor | undefined {
-    const codepoint = cell.getCode();
-    if (57344 <= codepoint && codepoint <=  63743) {
-      // powerline chars #3739
-      return undefined;
-    }
-    if (this._optionsService.rawOptions.minimumContrastRatio === 1) {
+    if (this._optionsService.rawOptions.minimumContrastRatio === 1 || isPowerlineGlyph(cell.getCode())) {
       return undefined;
     }
 

src/browser/renderer/RendererUtils.ts

@@ -9,3 +9,9 @@ export function throwIfFalsy<T>(value: T | undefined | null): T {
   }
   return value;
 }
+
+export function isPowerlineGlyph(codepoint: number): boolean {
+  // This range was established via
+  // https://apw-bash-settings.readthedocs.io/en/latest/fontpatching.html
+  return 0xE000 <= codepoint && codepoint <=  0xF8FF;
+}

src/browser/renderer/dom/DomRendererRowFactory.ts

@@ -12,6 +12,7 @@ import { color, rgba } from 'browser/Color';
 import { IColorSet, IColor } from 'browser/Types';
 import { ICharacterJoinerService } from 'browser/services/Services';
 import { JoinedCellData } from 'browser/services/CharacterJoinerService';
+import { isPowerlineGlyph } from 'browser/renderer/RendererUtils';
 
 export const BOLD_CLASS = 'xterm-bold';
 export const DIM_CLASS = 'xterm-dim';
@@ -225,8 +226,7 @@ export class DomRendererRowFactory {
   }
 
   private _applyMinimumContrast(element: HTMLElement, bg: IColor, fg: IColor, cell: ICellData): boolean {
-    const codepoint = cell.getCode();
-    if (this._optionsService.rawOptions.minimumContrastRatio === 1 || 57344 <= codepoint && codepoint <=  63743) {
+    if (this._optionsService.rawOptions.minimumContrastRatio === 1 || isPowerlineGlyph(cell.getCode())) {
       return false;
     }